Suction Caisson Capacity in Anisotropic, Purely Cohesive Soil

Abstract

This paper presents a plastic limit analysis of the lateral load capacity of suction caissons in an anisotropic, purely cohesive soil assuming conditions of rotational symmetry about the vertical or gravity axis. The formulation utilizes a form of the Hill yield criterion that is modified to allow for different soil strengths in triaxial compression and extension. Using this yield criterion, energy dissipation relationships are formulated for continuous and discontinuous deformation fields. These dissipation relationships are then applied to a postulated caisson failure mechanism comprising a wedge near the free soil surface (mudline), a two-dimensional flow-around failure at depth, and a hemispherical slip surface at the base of the rotating caisson. The plastic limit analysis predictions compared favorably to predictions obtained from finite-element simulations employing a Hill yield criterion. For the range of anisotropic undrained strength properties commonly reported for normally